Improvement in casting chilled mold-boards



. i NITED STATES PATEN GEORGE K. SMITH, OF WATERLOO, IOWA.

Specification forming part of Letters Patent No. 161,169, dated March23, 1875; application filed January 11, 1875.

To all whom it mag/- concern Be it known that I, GEORGE K. SMITH, ofWaterloo, in the county of Black Hawk and State of Iowa, have invented anew and useful Improvement in Casting Mold-Boards for Plows, and forother purposes, of which the following is a full, clear, and exactdescription, reference being made to the accompanying drawings.

The object of my invention is to prevent chilled castings from eitherwarping or cracking in cooling oli'. so that the perfect form of thepattern may be retained, while one side ot' the plate'may be hard, so asto be highly polished and durable, while the other and unchilled sidewill be soft, slightly elastic, and tenacious, thus preventing the hard,brittle side from being broken.

My invention consists in making a series of circular concave depressionson the inside of the pattern of the mold-board or plate that is to bechilled, in such a manner that, being distributed evenly over thesurface, at least one-half of the metal on the side thus indented isleft out of the plate in the casting.

In giving a further description, reference may be had to the drawings.

Figure l represents the face or chilled side of the mold-board. Fig. 2represent-s the inside of the mold-board, showing the circular concavedepressions. Fig. 3 shows an edge view of the same. Fig. 4 shows the topview ot' the plow-point. Fig. 5 shows the under side of the same.

The mold-boards of plows used in the rich soil of the western prairiesrequire to be highly polished to prevent the soil from adhering to theirsurface, and increasing the draft. To meet this requirement hardenedsteel plows have been used; but these are very expensive, and, moreover,are liable to break. Chilled cast-iron plows have been made at a muchless cost, which, when the mold-boards are ground and polished, arefully equal to the tempered steel plows. But the difficulty of castingthe mold-boards with one side hard for wear, and the other side soft,slightly iiexible, yet tenacious, so as to give them sufficient strengthwithout their warping out of shape or cracking the casting in coolingott', has been verygreat, as the chilled side of the plate contract-sabout twice as much as the soft side.

By making a series of circular concave depressions, a a, on the underside, so as to take out one-half of the soft metal, the plates A willcool oft' without cracking or warping out ot' their proper shape.

I am aware that elongated grooves arranged over a part of the unchilledsurface are not new; but

What I claim as my invention is- A series of circular concavedepressions in the plates, mold-boards, or other castings, evenlydistributed over the entire side, opposite the face to be chilled,substantially as and for the purpose herein shown.

In testimony whereof I hereunto subscribe my name.

GEORGE K. SII/HTH.

Witnesses:

GEo. W. MILLER, HENRY BARDEN.

